With the increasing use of letermovir and considering that haploidentical hematopoietic stem cell transplantation (haplo-HSCT) predominates in China alongside a high CMV seroprevalence in the population, multiple domestic centers have reported cases of CMV infection after letermovir discontinuation. Currently, there is no clear definition for the high-risk population who may benefit from extended letermovir prophylaxis. This study aims to utilize CMV-specific immune reconstitution to identify high-risk individuals for CMV infection after letermovir cessation post-transplant, thereby guiding the timing of letermovir discontinuation and balancing the risks and safety associated with prolonged prophylaxis.
CMV IgG-positive recipients undergoing HLA-haploidentical hematopoietic stem cell transplantation (HSCT).
CMV IgG-negative recipients receiving a graft from a CMV IgG-positive donor, and who have received letermovir as CMV prophylaxis post-transplant without prior discontinuation.
(2) Plasma CMV-DNA level below the lower limit of detection (local threshold: 400 copies/mL) within 5 days before enrollment.
(3) Age ≥ 18 years.
(1) Prior clinical diagnosis of CMV infection, CMV disease, or CMV viremia before enrollment;
(2) Received ganciclovir, valganciclovir, foscarnet, acyclovir (oral dose >3200 mg daily, or intravenous dose >25 mg/kg daily), valacyclovir (oral dose >3000 mg daily), or famciclovir (oral dose >1500 mg daily) within 7 days before enrollment;
(3) Received the following treatments within 30 days before enrollment: cidofovir, CMV hyperimmune globulin, any experimental anti-CMV therapy or biologics;
(4) Presence of uncontrolled infection, requirement for mechanical ventilation, or hemodynamic instability at enrollment;